Wednesday, June 26, 2013

How to Choose Tyres

What is the structure of a tyre?

How to read a sidewall? 

How to Choose Tyres

 1. You tire size

  • Your vehicle’s original equipment tyre size can be found in your owner's manual or on the tyre placard located on the driver’s door jamb, glove compartment door, or inside the fuel flap.
  • You can also check your existing tyre’s designation on the sidewall.

2. Your climate condition

Driving on a Wet Road

The characteristics of your vehicle’s tyres influence the braking distances on wet roads.

As soon as it rains, visibility decreases and the pavement become slippery because of the dust and oil on the road. On a wet road, the braking distance is three times longer than on a dry road. The condition of your tyres’ tread is important, because in a few thousandths of a second, the tread collects the water in its grooves and expellees it away from the contact area with the road.

- Groove to Tread Ratio (Percentage of Grooves)
The more grooves a tread pattern has and the greater their depth is, the greater the tread pattern’s ability to evacuate water .

- Siping
The ridges and sipes help to dry the pavement by acting as a “windscreen wiper". Wiping the water from the road surface so that the rubber can grip well with the dry surface.

On a wet road, a vehicle equipped with more worn tyres needs a longer distance to stop. Moreover, the risk of aquaplaning increases considerably.

Be especially careful during the first rain after hot periods. The dust and oil on the road make the road slippery.

Driving on a Dry Road

On a dry road, the more rigid your tyre’s tread pattern is, the more precise your driving will be.

The rigidity of the tread pattern is one of the key aspects that contribute to driving with precision and good vehicle handling. This tread rigidity is obtained through the:
- Tyre’s Profile
A flat profile with square shoulders provides a good foundation to the tyre, especially when negotiating a bend in the road

- Groove to Void Ratio
The lower the percentage of grooves, the greater the surface of rubber on the ground and the better the grip on a dry road surface.

- Solid Tread Blocks
Wide, solid tread blocks limit the tread pattern’s mobility in its thickness.

- Self-Locking Sipes
The sipes “erode” the rigidity of the tread pattern (bristle effect). To overcome this, complex self-locking sipes can be used.

3. Your usage condition

In the city

City driving requires that your tyres have characteristics specific to city constraints.
Tyre Selection Criteria:
- Braking Distance
To cope with all the hazards of city driving (pedestrian crossing without looking, etc.), you need tyres with the minimum braking distance, on both dry and wet roads.
- Longevity
Tyres undergo numerous stops and starts. Each tread block in contact with the road under the effect of engine or braking forces deforms and slides. Sliding and contact pressure scrape off material. Choose tyres with increased longevity.
- Fuel Economy
Tyres with low rolling resistance can effectively save fuel.

On Main Roads of Motorways

Tyres play a key role in your vehicle’s road handling because they provide, at the end of the chain, the necessary actions to maintain the vehicle’s trajectory at relatively high speeds.
Tyre Selection Criteria:
- Braking Distance at High Speed
For maximum safety, you need tyres with minimum braking distance on both dry and wet roads.
- Comfort
For long trips, choose tyres that offer comfort qualities both in terms of vibrations and noise level.
- Road Holding
Prefer a high-performance tyre.

Sports Car

You enjoy driving your vehicle in a sporty manner: the tyres are going to provide all the necessary actions to maintain the vehicle’s trajectory at relatively high speeds (consistent with road safety rules or on an authorized circuit).
Tyre Selection Criteria:
- Grip
Look for a tyre profile with excellent performances on dry and wet roads alike.
- Road Holding 
Choose tyres from the Sports line, which provide excellent directional precision and good stability in curves.


To drive a 4x4 off-road and maximize your enjoyment, it is not enough to adopt the right techniques. You also have to choose the right tyres.
Tyre Selection Criteria for Driving:
- On tracks
Mixed or A/T (All terrain) profiles can be used. The right choice is a robust tyre that provides major impact and cut resistance.
Do not under-inflate your tyres. Inflate to the maximum pressure to maximize resistance to impacts and pinching when driving at sustained speed.
- In sand
Deflate the tyres some to improve drivability. In some extremely difficult conditions you can lower your pressure but the speed must also be lowered. Once clearing the obstacle, reinflate your tyres to the manufacturers recommended pressure.
- In mud
Opt for a specific Mud tyre with big tread blocks. With this type of tread pattern, the “rack” effect is encouraged. This effect gives your vehicle the drivability it needs to get out of the mud.
Deflate the tyres some to improve drivability and “self-clean” the tyres.
Let the tyre work, avoiding excessive taps on the accelerator, which are synonymous with loss of grip.
Remember to reinflate after crossing the obstacle.
- In water
Maintain normal pressure in the tyres.
Drive slowly and maintain a constant speed to avoid creating any waves and spray.

Source: : How to choose tyre